Apparatus for assembling spark plugs



Jan. 25, 1938. A. M. BROWN 2,106,451

APPARATUS FOR ASSEMBLING SPARK PLUGS Filed Jan. 28, 1956 I 5 Sheets-Sheet l INVENTOR v Archibokd Brown ATTORNEY Jan. 25,.1938. BROWN 2,106,451

APPARATUS FOR ASSEMBLING SPARK PLUGS Filpd Jan. 28, 1936 5 Sheets-Sheet 2 ty z 43 ATTORNEY Jan. 25, 1938. BROWN 2,106,451

ARPARATUS FOR ASSEMBLING-SPARK PLUGS I Filed Jan. 28, 1936 5 Sheets-Sheet 3 mvzmon Avchlboli M. Brown ATTORNEY Patented Jan. 25, 1938 PATENT OFFICE APPARATUSFOR ASSEIWBLING SPARK PLUGS Archibald vM. Brown, Akron,

Ohio, assignor to The Firestone Steel Products Company, Akron, Ohio, a, corporation of Ohio Application January 28, 1936, Serial No. 61,162

14 Claims.

This invention relates to apparatusfor assembling spark plugs, and more especially it relates to improved mechanism for assembling the porcelains and metal washers in metal spark plug shells '5 of the crimped type.

Apparatus for the purpose mentioned as heretofore provided has not been satisfactory and has resulted in many spark plugs being rejected because of eccentricity of the central pole or elec- 10 trode, and large numbers of porcelains have been broken. The aforesaid difficulties have been due primarily to the fact that the porcelains are not uniformly of true shape, and the assembling apparatus has not been adapted to compensate for slight variations from true shape.

The chief objects of the invention are to avoid the rejections and breakage that heretofore obtained in the manufacture of spark plugs; and to improve the quality of the spark plugs by assur- 20 ing accurate concentricityof the porcelain of the plugs. More specifically the invention aims to provide apparatus of the character mentioned comprising means for accurately centering the porcelain with relation to the metal shell of a spark plug before the application of metal-deforming pressure upon the assembly. Other-objects will be manifest.

Of the accompanying drawings:

Figure 1 is a front elevation of apparatus em- 39 bodying the invention,in' its preferred form, shown in inoperative position in full linesand in operative position in broken lines, and the work therein;

Figure 2 is a section on the line'2-2 of Figure 1, on a larger scale, showing the respective elements in the position they assume in the first phase of operation;

Figure 3 is a view-of the elementsshown in Figure 2 as they appear in the final phase-of operation;

Figure 4 is a section on the line 44-of-Figure 3;

Figure 5 is a perspective =view of 'acentering plung r constituting one-element of the apparatus;

Figure 6 is a section-on theline 6-16 of Figure 3;

Figure 7 is a sectionon the line 1-1 of Figure 1;

Figure 8 is a vertical diametric sectionthrough the upper head of a modified embodiment of the invention, in inoperative position; and

to Figure 9 is a view of the elements shown in Figure 8 in operative relation to a lower head, and the work therebetween.

Referring to the drawings, particularlyjFigure 1 thereof, it] is the frame. of a machine. of the type known asa punch press lLis the table ,or bed plate thereof, I 2, I 2 are parallel, vertical guide- -ways formed on the frame above said bedplate, and l 3 is a slide movable in said guideways. The usual means (not shown) is-provided for reciproeating the slide l3 vertically in its guideways, said "5 means including a one-revolution clutch which causes the slide to descend and rise once during a cycle of operation of the apparatus. The apparatus for operating upon the spark plugs is carried in part upon the bed plate I l and in part by the slide l3. Said apparatus consists of two units, one of which is designated A and serves to assemble a porcelain, metal shell, and metal gaskets in proper concentric relation and. to deform said gaskets; the other unit, designated B, serves to" crimp the metal shell to confine the porcelain and gaskets'therein. V

Suitably mounted upon the bed plate I l of the apparatus is a die shoe l5 that includes apair of pressure blocks, such as the pressure block [6,U

Figures 2 and 3, the latter being mounted upon the upper end of an upwardly urged rod 1-! and having its upper face flush with the top face of the die shoe l5. Secured to the top of the die shoe I5 is a die holder I8 that carries the die elements of 5 thecentering unit A and the crimping unit B. Suitably secured to the bottom face of the slide I3 is a punch holder 19 that carries the punchelements of the centering unit A and crimping unit B. The details of the centering unit A will be described first, attention being directed especially to Figures 2, 3-and 4.

'Mounted within a-vertical, through bore 2| in the die holder I8 is a cylindrical centering die 22 that rests upon the upper face of pressureblock ai l6, said centering die being retained in said bore by an apertured face plate 23 that is secured to the top-face of the die holder and overlies a shoulder 24 formed on the said die near the upper end thereof, the top of the die projecting above the top p of the face plate. The centering die 22 is formed. with anaxial bore 25 that is substantially smaller in diameter in its medial region than at therespective end portions thereof, the arrangement being such as to provide a ledge or shoulder 26 at the. upper end of the medial region of the bore and a shoulder 21 at the lower end thereof.

Slidably mounted in the lower end portion of bore 25 is acentering plunger 29 that has an upward extension 29a of reduced diameter that is ,50 slidable-within the reduced medial portion of the bore 25. Upwardly of extension 29a the plunger is formedwith a. furtherreduced portion 29b of such diameter as to fit nicely within the bore of ,a spark plug shell at the lower end of the latter. 5

The upper terminal portion of the plunger extension 29?) is still further reduced in diameter, as shown at 230, so as to have a clearance of at least inch with the wall of the plug-shell-bore for a purpose presently to be explained. The plunger 29 is formed with an axial bore 30 that is relatively small at its upper end portion to receive and confine the central electrode that projects from the lower end of the porcelain of the work, the upper terminus of bore 30 having a flared or countersunk orifice 3| adapted to receive the lower end of said porcelain. Portions 29a, 29b and 290 of the plunger 29 are diametrically slotted at 32, which slot is of such width as to accommodate the angular electrode secured to the metal shell of a spark plug. The lower end portion of the plunger-bore 30 is of larger size so as to accommodate a compression spring 33. The latter rests upon the top of pressure block I6 and urges the plunger 29 upwardly, the upward movement of the plunger being limited by the shoulder 21 which abuts the shoulder on the plunger at the bottom of extension 23a thereof.

The ledge or shoulder 25 in the centering die 22 constitutes a seat for the work to be operated upon by the apparatus. Said work comprises a tubular metal shell 35, a porcelain 36, and upper and lower deformable metal gaskets 31 and 38 respectively. The porcelain includes a central metal electrode 39 that projects somewhat from the lower end thereof, and the usual angular, ground electrode it projects from the lower end of the metal shell 35. When mounted in the apparatus initially, the usual shoulder near the lower end of the shell rests upon ledge 26 in centering die 22, the extension 2% of plunger 29 fitting easily within the lower end of the bore of the shell and electrode 43 fitting within slot 32 of the plunger.

The electrode 39 of the porcelain 36 fits snugly within bore 36 of the plunger, and the lower end of the porcelain rests in countersink 3| in the top of the plunger. Because the spring 33 normally holds the plunger in raised position, the porcelain 35 is consequently held in an elevated position as compared to its final, assembled position within the shell 35, as is most clearly shown in Figure 2. Gaskets 31 and 38 encircle the porcelain above and below the enlarged medial portion of the latter.

The punch mechanism of the centering unit of the apparatus comprises a tubular bushing 42 that is mounted within a vertical bore 63 in the punch holder 19 and removably retained therein by a set screw 44. The bushing 42 has its bore interiorly threaded at its lower end portion, and threaded thereinto is a tubular punch holder 45. The lower end of the latter is formed with a radially inwardly extending flange 45a, and exteriorly is of hex agonal shape as shown in Figure 6, to permit of engagement by a turning tool such as a wrench. A look nut 43 is threaded onto the exterior of punch holder 45 for securing it in proper axial position within bushing 42.

Slidably mounted within the center bore of the punch holder 5 is a tubular centering punch 48, the lower end of which is formed with an inwardly extending circumferential flange 481], that normally rests upon flange 45a. of the punch holder in the inoperative position of the apparatus. The inner perimeter of said flange 48a is formed with a concentric, downwardly-extending portion 48b of such inside diameter as to circumscribe a porcelain 3S and'to engage the upper metal gasket 31 thereon, and of such length and outside diameter as to enter the upper end of the boreof shell 35 during the operation of the apparatus. Mounted within punch 48 and resting upon flange 48a. at the bottom thereof is a ring 53 of deformable material such as rubber, said ring fitting snugly within the punch and having an inside diameter somewhat larger than the upper tapered portion of a porcelain 35. Resting upon the top of the rubber ring 50 is a tubular metal spacer 5i that slidably fits within the bore of punch 13, and above the latter is of larger outside diameter so as to have a sliding fit with the bore of punch holder 45. .Above the spacer a pair of nuts 52 are threaded into the bore of the punch holder for retaining the spacer therein. The inside diameter of the spacer 5i preferably is the same as the inside diameter of the ring 59 so that the upper end portion of a porcelain 35 may be received therein. The reduced lower end portion of the spacer 5|, which fits within punch 8, is of such length as to permit limited axial movement of the spacer relatively of the punch upon deformation of the ring 50 when under compression. The resistance to compression of the rubber ring 50 is less than that of the spring 33 which opposes it in the operation of the apparatus as now will be explained.

The operation of the centering unit A of the apparatus is as follows: With the press in the inoperative position shown in full lines in Figure 1 of the drawings, a loosely assembled spark plug is mounted in die portion of the apparatus wherein it assumes the position shown in Figure 2 as previously described. The press mechanism is then actuated to effect an operative cycle of the apparatus wherein the slide l3 of the press descends and then rises again. As the slide I3 moves downwardly, the punch structure telescopes with the spark plug elements as shown in Figure 2, and the tubular extension 4812 of the punch 48 engages the upper gasket 37 on the porcelain 35 of the spark plug. The spring 33 resists downward movement of the porcelain 35, with the result that downward movement of the punch 48 temporarily ceases, and continued downward movement of the spacer 5! with other parts of the punch structure applies a compressive force upon the rubber ring 50. The latter is thereby deformed and distended radially inwardly so that it grips the upper tapered portion of the porcelain 35 and centers it exactly. As the pressure upon the rubber ring increases, the resistance of spring 33 is overcome and plunger 23 is moved downwardly thereby permitting porcelain 36 and upper gasket 31 to move downwardly in the shell 35 until said porcelain engages lower gasket 38 in said shell. Compression of ring 50 also permits spacer 5| to move axially downwardly relatively of punch 48 so that in the fully compressed condition of ring 53 the upper end of the punch is in abutting relation with the shoulder at the base of the enlarged upper portion of said spacer, as shown in Figure 3.

Thus the full force of the descending slide I3 is translated to the punch for pressing and deforming the gaskets 3'! and 3B in the spark plug shell, while the porcelain is held in properly centered position in the manner described. As shown in Figure 3, when the plunger 29 is moved downwardly to its lowermost position by the pressure of the porcelain 36, portion 23b of the plunger is below the lower end of the shell 35 and only the smaller terminal portion 290 of the plunger is within the bore of the said shell. This permits of slight lateral movement of the shell 35 on its seat 26, relatively of the plunger 29, to

I 2,106,45 1 :compensate: for-any irregularitiesjn'thet shape of the "porcelain. Anyexcessive "pressure 'of'the centering mechanism upon the spark .plug :ele-

ments will'be transmitted to thecentering die 'each other so that thereafter they maybe handled as a unit without disturbing the perfect concentricity of the. parts. When the slide l3rises,

the work is.:partly'- ejected from the die structure by the plunger 29 which rises under the impetus ofspring 33. "This completes acycle:of operation of the centering unit.

The crimping 'runit .B, 'for convenience, is

rmounted in the-same pressas the centering unit A, beside'thelatter. The details of the crimp- 'ing unit are shown in Figure 7 to which .attention now is directed.

-Mounted in a vertical bore 55 in the die holder [8, beside centering die 22, is a cylindrical crimping die 56'that.is identical with said centering die .and is retained in the same manner as the latter by face plate 23. The work as it comes from the centering unit is received in the axial bore of the crimping die, and seats upon a ledge therein identical-withthe ledge 26 of the said centering die, there being no plunger within the bore of the crimping die.

The punch mechanism of the crimping unit is mounted in the punch holder l9 hereinbefore described. It comprises an axially apertured punch 58 that is mounted in a shallow recess-59 in'the'bottom face of punch holder IS, the top face ofsaid punch being concave and engaging the complementally convex bottom 'face of an axially apertured centering plate 60 also mounted in said recess, the arrangement constituting a ball and socket connection between said members. The punch 58'and centeringplate 60 are retained in said recess by a retaining plate 6| mounted upon the bottom face of punch holder l9, said retaining plate being formed with an aperture through which the punch extends. The plate aperture is formed with a circumferential, inwardly extending flange Bla engageable with an outwardly extending circumferential flange 58a on'the upper end-of the punch 58, the arrangement being such as to permit limited axial movement'of the punch and centering plate relatively of thepunch holder [9 and plate 6|. The centering plate 60 is backed by a compression spring 62 seated in a bore 63 in the punchholder I 9, which spring normally urges the punch and centering plate downwardly. An annular punch-filler 64 is seated with a force fit in an axial recess in the bottom of the punch. Both annular corners of the inner-periphery of the punch filler-64 are grooved or concaved, as shown at-55, 65 so as to effect a crimping of the open end of a spark plug shell 35 when forcibly pressed thereagainst. The axial apertures in the punchfiller, punch, and centering plate receive the porcelain 36 of a spark plug during a crimping operation. The positionof the punch-filler 64 may be reversed and the grooves 65 used alternatively as either becomes worn.

In the operation of the crimping unit B, an assembled, centered spark plug as it comes from the centering unit A is mountedin the crimping die 56 as shown. When the slide I3 is caused to descend, the punch-filler-Sd and punch 58 telescope with the work, it being understood that the punch flange 58ais'bearing against the re- .most nut 52. The axial rtaining; plate flange. Glarat: this time. When' the punch fill-er 64 engages the openxupper margin of the shell 35 of the spark plug=with itsgroove 65, downward movement of the punchand. punch 'filler temporarily ceases, continued downward movement of the punch holder l9 and slidel3 servingto compress the spring 62. At this time,

because of theball and socket joint betweencentering plate:60 and punch58, the latter ispermittecl such. movement relatively of the spark .1 plug. as. to effect accurate centering of the punchfiller-fi l upon the top margin of the spark plug.

As soon asrelative axial-movement of thepunch -58 and punch holder-I9 carries centering plate fillto the bottom of recess 59, the full'force of the punch holder is transmitted to the punchfiller 54 and crimping of the open margin of the spark plug shell 35 onto the gasket 31 is effected,

as is clearly shown in Figure 7. The .slide l3 then rises to inoperative position thus completing the cycle of operation.

The invention assures concentricity of the spark plug elements, largely eliminates breakage of porcelains, and achieves the other objects set out in theforegoingstatement of objects.

In the embodiment of the invention shown in :Figures 8 and 9 the diemechanism of thecentering unit is identical with the die mechanism of the previously described centering unit A- The punch mechanism is somewhat .similar to that previously'described and includes a number of identical elements, namely,'the punch holder l9, bushing 42,'punch holder '45, lock nut 46, and spacer-retaining .nuts 52, 52. "Slidably. mounted within the central bore of the punch holder is a centering punch 68 consisting of an annular disc-like structure having a down wardly extending circumferential flange 68a formed about its inner. periphery. Saidflange is of such inside diameter as to circumscribe the porcelain 36 of a sparkplug and to engage the upper metal. gasket31 thereon when the loosely assembled spark plug isin the die mechanism of the centering unit. The die 68 normally rests.

upon the inwardly directed flange 4.5a at the lower end of the punch holder 45. superposed vuponthe punch :68, within the bore of the bushing 42, is an annular-rubber.ring--B9,.and.superposed upon the latter is a tubular metal spacer,

ill, the upper end of the latter abutting the lower openings in the ring 69 and spacer-10 are of such size as toreceivethe tapered upper end portion of a porcelain 35 of a spark'plug.

The operation of this embodiment-of them-" vention is substantially the same as that previously described. As the slide l3 descends, flange 68a'of punch 68 engages .upper gasket 31 of the spark plug assembly andstops, further. movement of the other elements of the .punch structure serving to compress and deform rubber ring 69 so that it engages and centers the porcelain of the spark plug. Pressure upon the rubber ring increases until it overcomes the. resistance of the yielding support 29.for the porcelain 36, and the latter moves downwardly and the gaskets 3'! and 38 are deformed in the same manner as in the previously described embodiment, except that all of the deforming-pressurezm is transmitted through the deformable rubber ring 69. 7

Other modification may be resorted to without departing from the spiritof the invention or thescope of-the-appended claims, which are notr7 limited wholly to the specific construction shown and described.

What is claimed is:

1. Apparatus for assembling spark plugs, said apparatus comprising a relatively stationary support for the metal shell of a spark plug, a yielding support for the porcelain thereof adapted normally to hold said porcelain in partly telescoped relation to said shell, a punch structure for moving said porcelain into fully telescoped relation to said shell and for deforming the metal gaskets about the porcelain, and means adapted to engage the porcelain and to position it concentrically with relation to the punch before the latter moves the porcelain toward fully telescoped relation with the shell, said porcelain centering means being operated by the pressure of the punch upon the porcelain.

2. Apparatus for assembling spark plugs, said apparatus comprising a relatively stationary support for the metal shell of a spark plug, a yielding support for the porcelain thereof engaging the lower end of said porcelain and normally holding the latter elevated in partly telescoped relation to said shell, a reciprocable punch structure engageable with the upper gasket about the porcelain for moving said porcelain downwardly into fully telescoped relation to said shell with sufficient pressure to deform both metal gaskets about said porcelain, a porcelain centering device carried by the punch structure adapted to engage the porcelain to position it concentrically of the punch, and means for operating said porcelain centering device by means of the pressure exerted by the punch structure upon the porcelain.

3. In spark plug assembling apparatus, the combination of a relatively stationary support for a metal shell, a yielding support for a porcelain adapted to hold the latter elevated in partly telescoped relation to said shell, a reciprocable punch adapted to force the porcelain into said shell, against the pressure of the yielding support of the porcelain, and a constrictable centering device adapted to engaging a peripheral region of the porcelain to center it with relation to the punch, and means responsive to pressure of the punch against the porcelain for effecting constriction of said centering device.

4. In spark plug assembling apparatus, the combination of a relatively stationary support for a metal shell, a yielding support for a porcelain adapted to hold the latter elevated in partly telescoped relation to said shell, a reciprocable punch adapted to force the porcelain into said shell, against the pressure of said yielding support of the porcelain, a porcelain-centering device of deformable material adapted to engage the porcelain and center it with relation to the punch, and means for deforming said centering device prior to the telescoping of the shell and porcelain under impetus of the punch.

5. In spark plug assembling apparatus, the combination of a relatively stationary support for a metal shell, a retractible support for a porcelain adapted-to hold the latter elevated in partly telescoped relation to said shell, a reciprocable punch adapted to force the porcelain into fully telescoped relation to said shell, a porcelain centering device of deformable material adapted to be deformed into engagement with the perimeter of the porcelain to center it with relation to the punch, said device being deformed by the resistance of the porcelain to movement under pressure of the punch, and means for utilizing the pressure of the punch upon the porcelain for retracting the porcelain support after the centering device has been deformed.

6. In spark plug assembling apparatus, the combination of a relatively stationary support for a metal shell, a retractible support for a porcelain adapted to hold the latter elevated in partly telescoped relation to said shell, a reciprocable punch adapted toforce the porcelain into fully telescoped relation to said shell, a porcelain centering device of deformable material adapted to engage the porcelain and center it with relation to the punch, said device being deformed by the resistance of the porcelain to movement under pressure of the punch, and a yielding backing for the porcelain support having greater resistance to deformation than said centering device, whereby the latter functions before the porcelain moves downwardly into the shell.

7. In spark plug assembling apparatus, the combination of a relatively stationary support for a metal shell, a retractible support for a porcelain adapted to hold the latter elevated in partly telescoped relation to said shell, a reciprocable punch adapted to force the porcelain into fully telescoped relation to said shell, a porcelain centering device consisting of a rubber ring carried by the punch structure adapted to be deformed and constricted upon the porcelain to center the latter with relation to the punch, when the punch engages the porcelain, and a compression spring backing the retractible porcelain-support, said spring having greater resistance to compression than said rubber ring whereby the ring is deformed to center the porcelain before the spring yields to permit telescoping movement of the porcelain.

8. Apparatus for assembling spark plugs, said apparatus comprising an annular punch, a deformable rubber ring concentric therewith, and means for deforming the rubber ring against a portion of the spark plug assembly to center said portion with relation to the punch in timed relation to the operation of the punch upon a spark plug assembly.

9. Apparatus for assembling spark plugs, said apparatus comprising an annular punch, means for forcing the latter into engagement with a spark plug assembly, and a deformable rubber ring concentric with said punch and constituting a yielding backing for the latter, said ring being deformed under pressure and constricted about a portion of the spark plug assembly to center the same with relation to the punch.

10. Apparatus for assembling spark plugs, said apparatus comprising a reciprocable punch support, an annular punch carried thereby, said punch being movable axially, relatively of said support, a concentric annular ring of deformable material constituting a backing for said punch, said ring being so confined as to reduce in diameter upon compression when the punch is forced against a spark plug assembly, and thereby to constrict about a portion of the latter to center it relatively of the punch.

11. Apparatus for assembling spark plugs, said apparatus comprising a relatively stationary support for a metal shell, a retractible device engageable with the shell for centering it on said support, means for forcing a porcelain into telescoped relation with said shell, and means for utilizing the movement of the porcelain to withdraw the retractible device from engagement with the shell as the porcelain moves thereinto.

12'. In apparatus of the character described, the combination of a relatively stationary support for a tubular metal shell, a retractible device engageable within the lower end portion of the shell for determinately positioning the shell on its support, and means for forcing a porcelain into telescoped relation with said shell, said retractible device being so constructed and arranged as to be depressed and moved out of engagement with the shell by pressure of the porcelain against its upper end.

13. In apparatus of the character described, the combination of a support for a tubular metal shell, a yieldingly mounted device engageable within the lower end portion of the shell for determinately positioning the shell on said support, said device being adapted to support a porcelain in elevated, partly telescoped relation to the shell, and means for forcing the porcelain downwardly into fully telescoped relation to the shell, said yielding device being so constructed as to be depressed out of engagement with the shell to permit a modicum of movement of the latter relatively of its support before the porcelain is fully seated.

14. In apparatus of the character described, the combination of a support for a tubular metal shell, a yieldingly mounted device therein having a generally cylindrical upper end portion adapted slidingly to fit within the bore of said shell, there being a terminal region of reduced diameter on said upper end portion, and means for forcing a porcelain into fully telescoped relation with said metal shell, said yielding device being so positioned as to be engaged by said porcelain and depressed during the telescoping operation whereby its upper end portion is moved out of contact with the bore of the shell by reason of the reduced diameter of its terminal region.

ARCHIBALD M. BROWN. 

